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  1. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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  4. <TITLE>File Wrappers</TITLE>
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  9. <!-- Begin Banner -->
  10. <H1 CLASS="title">File Wrappers</H1>
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  13. <DL class="page-index">
  14. <DT><A href="#overview">Overview</A></DT>
  15. <DT><A href="#headers">Headers</A></DT>
  16. <DT><A href="#reference">Reference</A>
  17. <UL>
  18. <LI CLASS="square"><A href="#file_source">Class template <CODE>basic_file_source</CODE></A></LI>
  19. <LI CLASS="square"><A href="#file_sink">Class template <CODE>basic_file_sink</CODE></A></LI>
  20. <LI CLASS="square"><A href="#file">Class template <CODE>basic_file</CODE></A></LI>
  21. </UL>
  22. </DT>
  23. </DL>
  24. <HR>
  25. <A NAME="overview"></A>
  26. <H2>Overview</H2>
  27. <P>
  28. The class templates <CODE>basic_file_source</CODE>, <CODE>basic_file_sink</CODE> and <CODE>basic_file</CODE> are wrappers for <CODE>std::basic_filebuf</CODE> which are <A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A>. They are useful whenever one wants to access a file without managing the lifetime of a standard file stream or stream buffer. This is because when a stream or stream buffer is added to a <A HREF="filtering_streambuf.html"><CODE>filtering_streambuf</CODE></A> or <A HREF="filtering_stream.html"><CODE>filtering_stream</CODE></A> it is stored as a reference which must remain valid until that stream or stream buffer is removed from the chain.
  29. </P>
  30. <P>
  31. The most common specializations are accessible via the typedefs <CODE>file_source</CODE>, <CODE>file_sink</CODE>, <CODE>file</CODE>, <CODE>wfile_source</CODE>, <CODE>wfile_sink</CODE> and <CODE>wfile</CODE>.
  32. </P>
  33. <A NAME="headers"></A>
  34. <H2>Headers</H2>
  35. <DL class="page-index">
  36. <DT><A CLASS="header" HREF="../../../../boost/iostreams/device/file.hpp"><CODE>&lt;boost/iostreams/device/file.hpp&gt;</CODE></A></DT>
  37. </DL>
  38. <A NAME="reference"></A>
  39. <H2>Reference</H2>
  40. <A NAME="file_source"></A>
  41. <H3>Class template <CODE>basic_file_source</CODE></H3>
  42. <H4>Description</H4>
  43. <P>
  44. <A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in read-only mode.
  45. <P>
  46. <A NAME="file_source_synopsis"></A>
  47. <H4>Synopsis</H4>
  48. <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
  49. <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">Ch</A>&gt;
  50. <SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_source_params">basic_file_source</A> {
  51. <SPAN CLASS="keyword">public</SPAN>:
  52. <SPAN CLASS="keyword">typedef</SPAN> Ch char_type;
  53. <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category;
  54. <A CLASS="documented" HREF="#basic_file_source_constructor">basic_file_source</A>( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  55. std::ios_base::openmode mode =
  56. std::ios_base::in );
  57. <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_source_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
  58. <SPAN CLASS="omitted">...</SPAN>
  59. };
  60. <SPAN CLASS="keyword">typedef</SPAN> basic_file_source&lt;<SPAN CLASS="keyword">char</SPAN>&gt; <SPAN CLASS="defined">file_source</SPAN>;
  61. <SPAN CLASS="keyword">typedef</SPAN> basic_file_source&lt;<SPAN CLASS="keyword">wchar_t</SPAN>&gt; <SPAN CLASS="defined">wfile_source</SPAN>;
  62. } } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
  63. <A NAME="basic_file_source_params"></A>
  64. <H4>Template parameters</H4>
  65. <TABLE STYLE="margin-left:2em">
  66. <TR>
  67. <TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
  68. <TD>The character type.</TD></TR>
  69. <TR>
  70. </TABLE>
  71. <A NAME="basic_file_source_constructor"></A>
  72. <H4><CODE>basic_file_source::basic_file_source</CODE></H4>
  73. <PRE CLASS="broken_ie"> basic_file_source( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  74. std::ios_base::openmode mode );</PRE>
  75. <P>
  76. Constructs a <CODE>basic_file_source</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
  77. <PRE CLASS="broken_ie"> mode |= std::ios_base::in;
  78. mode &amp;= ~std::ios_base::out;
  79. buf.open(path.c_str(), mode);</PRE>
  80. </P>
  81. <A NAME="basic_file_source_is_open"></A>
  82. <H4><CODE>basic_file_source::is_open</CODE></H4>
  83. <PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
  84. <P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
  85. <A NAME="file_sink"></A>
  86. <H3>Class template <CODE>basic_file_sink</CODE></H3>
  87. <H4>Description</H4>
  88. <P>
  89. <A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in write-only mode.
  90. <P>
  91. <A NAME="file_sink_synopsis"></A>
  92. <H4>Synopsis</H4>
  93. <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
  94. <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">Ch</A>&gt;
  95. <SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_sink_params">basic_file_sink</A> {
  96. <SPAN CLASS="keyword">public</SPAN>:
  97. <SPAN CLASS="keyword">typedef</SPAN> Ch char_type;
  98. <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category;
  99. <A CLASS="documented" HREF="#basic_file_sink_constructor">basic_file_sink</A>( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  100. std::ios_base::openmode mode =
  101. std::ios_base::out );
  102. <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_sink_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
  103. <SPAN CLASS="omitted">...</SPAN>
  104. };
  105. <SPAN CLASS="keyword">typedef</SPAN> basic_file_sink&lt;<SPAN CLASS="keyword">char</SPAN>&gt; <SPAN CLASS="defined">file_sink</SPAN>;
  106. <SPAN CLASS="keyword">typedef</SPAN> basic_file_sink&lt;<SPAN CLASS="keyword">wchar_t</SPAN>&gt; <SPAN CLASS="defined">wfile_sink</SPAN>;
  107. } } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
  108. <A NAME="basic_file_sink_params"></A>
  109. <H4>Template parameters</H4>
  110. <TABLE STYLE="margin-left:2em">
  111. <TR>
  112. <TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
  113. <TD>The character type.</TD></TR>
  114. <TR>
  115. </TABLE>
  116. <A NAME="basic_file_sink_constructor"></A>
  117. <H4><CODE>basic_file_sink::basic_file_sink</CODE></H4>
  118. <PRE CLASS="broken_ie"> basic_file_sink( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  119. std::ios_base::openmode mode );</PRE>
  120. <P>
  121. Constructs a <CODE>basic_file_sink</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
  122. <PRE CLASS="broken_ie"> mode |= std::ios_base::out;
  123. mode &amp;= ~std::ios_base::in;
  124. buf.open(path.c_str(), mode);</PRE>
  125. </P>
  126. <A NAME="basic_file_sink_is_open"></A>
  127. <H4><CODE>basic_file_sink::is_open</CODE></H4>
  128. <PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
  129. <P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
  130. <A NAME="file"></A>
  131. <H3>Class template <CODE>basic_file</CODE></H3>
  132. <H4>Description</H4>
  133. <P><A HREF="http://www.boost.org/libs/utility/CopyConstructible.html" TARGET="_top">CopyConstructible</A> and <A HREF="http://www.boost.org/libs/utility/Assignable.html">Assignable</A> wrapper for a <CODE>std::basic_filebuf</CODE> opened in read-write mode by default.
  134. <A NAME="file_synopsis"></A>
  135. <H4>Synopsis</H4>
  136. <PRE CLASS="broken_ie"><SPAN CLASS="keyword">namespace</SPAN> boost { <SPAN CLASS="keyword">namespace</SPAN> iostreams {
  137. <SPAN CLASS="keyword">template</SPAN>&lt;<SPAN CLASS="keyword">typename</SPAN> <A CLASS="documented" HREF="#basic_file_params">Ch</A>&gt;
  138. <SPAN CLASS="keyword">class</SPAN> <A CLASS="documented" HREF="#basic_file_params">basic_file</A> {
  139. <SPAN CLASS="keyword">public</SPAN>:
  140. <SPAN CLASS="keyword">typedef</SPAN> Ch char_type;
  141. <SPAN CLASS="keyword">typedef</SPAN> <SPAN CLASS="omitted">implementation-defined</SPAN> category;
  142. <A CLASS="documented" HREF="#basic_file_constructor">basic_file</A>( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  143. std::ios_base::openmode mode =
  144. std::ios_base::in | std::ios_base::out );
  145. <SPAN CLASS="keyword">bool</SPAN> <A CLASS="documented" HREF="#basic_file_is_open">is_open</A>() <SPAN CLASS="keyword">const</SPAN>;
  146. <SPAN CLASS="omitted">...</SPAN>
  147. };
  148. <SPAN CLASS="keyword">typedef</SPAN> basic_file&lt;<SPAN CLASS="keyword">char</SPAN>&gt; <SPAN CLASS="defined">file</SPAN>;
  149. <SPAN CLASS="keyword">typedef</SPAN> basic_file&lt;<SPAN CLASS="keyword">wchar_t</SPAN>&gt; <SPAN CLASS="defined">wfile</SPAN>;
  150. } } <SPAN CLASS='comment'>// End namespace boost::iostreams</SPAN></PRE>
  151. <A NAME="basic_file_params"></A>
  152. <H4>Template parameters</H4>
  153. <TABLE STYLE="margin-left:2em">
  154. <TR>
  155. <TD><I>Ch</I></TD><TD VALIGN="top">-</TD>
  156. <TD>The character type.</TD></TR>
  157. <TR>
  158. </TABLE>
  159. <A NAME="basic_file_constructor"></A>
  160. <H4><CODE>basic_file_::basic_file</CODE></H4>
  161. <PRE CLASS="broken_ie"> basic_file( <SPAN CLASS="keyword">const</SPAN> std::string&amp; path,
  162. std::ios_base::openmode mode );</PRE>
  163. <P>
  164. Constructs a <CODE>basic_file</CODE> which wraps a <CODE>std::basic_filebuf</CODE> <CODE>buf</CODE> opened as follows:
  165. <PRE CLASS="broken_ie"> mode |= std::ios_base::in | std::ios_base::out;
  166. buf.open(path.c_str(), mode);</PRE>
  167. </P>
  168. <A NAME="basic_file_is_open"></A>
  169. <H4><CODE>basic_file::is_open</CODE></H4>
  170. <PRE CLASS="broken_ie"> <SPAN CLASS="keyword">bool</SPAN> is_open() <SPAN CLASS="keyword">const</SPAN>;</PRE>
  171. <P>Returns <CODE>true</CODE> if the underlying instance of <CODE>basic_filebuf</CODE> was opened successfully.</P>
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  174. <P CLASS="copyright">&copy; Copyright 2008 <a href="http://www.coderage.com/" target="_top">CodeRage, LLC</a><br/>&copy; Copyright 2004-2007 <a href="https://www.boost.org/users/people/jonathan_turkanis.html" target="_top">Jonathan Turkanis</a></P>
  175. <P CLASS="copyright">
  176. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at <A HREF="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>)
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